A case-referent (control) study will be performed utilizing clinically diagnosed cases of Alzheimer's disease in order to evaluate an etiologic association with occupational exposure to solvents and/or lead. The cases will consist of all males ages thirty to sixty-five at time of first diagnosis. Occupational and sociological information will be obtained by questionnaire from closest living relative or acquaintance. A matched-pairs analysis will be performed to test the hypothesis that males with occupational exposure to solvents and/or lead are at increased risk of developing presenile dementia of the Alzheimer's type.